Self-Exited Oscillation in a Combustion Chamber Driven by Phase Change in the Liquid Fuel Feed System

Abstract

A new mechanism for the generation of a self-exited oscillation of combustion in a generic combustion chamber typical for aero-engine combustors is described. The cause of the oscillation is the phase change from liquid to vapour which happens when the preheat temperature of the air flowing through the burner exceeds the boiling temperature at the operating pressure and the fuel flow is so low that heat transfer to the liquid fuel causes evaporation within the fuel channels of the burner. Liquid fuel and vapour alternatively enter the airstream of the burner. This leads to an instable situation for the flame. Measurements of chemiluminescence and liquid fuel show nearly complete extinction and reignition for the limit cycle. Prevention of the oscillation is possible by better thermal management on the fuel path.